Circuit/System Description
The radio receives a vehicle speed signal from the electronic brake control module (EBCM) in order to correlate actual vehicle speed to the movement of the vehicle calculated by the navigation system and reported serial data.
Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier (if equipped) have a DC bias voltage that is one half of the battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5 V DC. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound. This voltage will vary depending on what type of audio is being listened to, talk or music, and type of music, as well as the volume setting of the system. Low volume and talk settings will measure around 1V AC and less, where constant music may measure 3 V AC and slightly higher. In an amplified audio system, these similar AC voltage measurements may be slightly higher on the output of the amplifier, and the typical AC voltage readings at the output of the radio are less than 1V AC.
The digital radio receiver (DRR) receives an XM satellite radio signal via the digital radio antenna. This signal is passed to the DRR through the digital radio antenna coax. The DRR sends a varying AC mV signal through separate left and right audio circuits (+ and -) to the radio. The voltage amount and rate of change is dependent upon the type of signal being received. The radio then processes these signals and passes the audio to the appropriate speakers or amplifier.
The radio provides a remote amplifier mute output circuit to control overall muting of the remote amplifier. The amplifier receives pulse width modulated (PWM) signals on the control circuit at varying duty cycle percentages for controlling muted and unmuted functions of the amplifier. Circuitry internal to the radio monitors the remote amplifier mute circuit for faults and sets the appropriate DTC when faults are detected.
The radio can control the video display mode on vehicles equipped with rear seat entertainment (RSE) video. The radio varies a pulse with modulated (PWM) signal to the rear entertainment video screen to command the display mode.
The radio can control the video display brightness on vehicles equipped with rear seat entertainment (RSE) video. The radio varies a pulse with modulated (PWM) signal to the rear entertainment video screen to command the screen brightness to the desired level.
The infrared module is supplied with 10.5 volts from the rear audio/HVAC module when the rear audio system is active. The infrared module is permanently grounded at G300.
The communication interface module (CIM) provides the cellular phone microphone with a supplied voltage on the cellular phone microphone signal circuit. When the microphone is in use, voice data from the user is sent back to the CIM on the signal circuit. The CIM provides a ground for the microphone via the low reference circuit.
The communication interface module (CIM) receives information from a specific GPS antenna located on the outside of the vehicle. The GPS antenna is connected to the CIM via a shielded coaxial cable. The antenna cable also provides a path for DC current for powering the antenna.
The cellular antenna is connected to the communication interface module (CIM) with a RG-58 coax cable. The CIM polls the data from the cellular antenna once every second.
The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center, and OnStar® Emergency. The communication interface module (CIM) supplies the OnStar® button assembly with 10 V via the keypad supply voltage circuit. Each of the buttons, when pressed, completes the circuit across a resistor allowing a specific voltage to be returned to the CIM over the keypad signal circuit. Depending upon the voltage range returned, the CIM is able to identify which button has been activated.
The Bluetooth ® antenna is a small fixed antenna connected directly to the communication interface module (CIM) and is used to send and receive signals from a Bluetooth ® enabled cellular phone. The antenna utilizes no cabling and is not external to the vehicle.
The audio/video adaptor allows the connection of audio and video signals from an external device such as a camcorder, video game console or MP3 player to the rear seat entertainment system. The middle jack is for left audio (white), the right jack is for right audio (red), and the left jack is for video (yellow). The system requires standard RCA cables to connect your external device to the RCA jacks. The auxiliary audio and video circuits are connected to the radio.
The Bluetooth ® antenna is a small fixed antenna connected directly to the communication interface module (CIM) and is used to send and receive signals from a Bluetooth ® enabled cellular phone. The antenna utilizes no cabling and is not external to the vehicle.
In order to use hands-free calling, the cellular phone must be paired to the vehicle. Up to five devices can be paired to the vehicle at one time, but only one can be connected at any given time. To pair a phone, the customer must know how to operate the Bluetooth ® functionality of their phone. The pairing process must only be done one time for each phone, unless that phone's information is deleted. For safety reasons, the pairing process is disabled while the vehicle is moving.
The digital radio receiver (DRR) receives an XM satellite radio signal via the digital radio antenna. This signal is passed to the DRR through the digital radio antenna coax. The DRR sends a varying AC mV signal through separate left and right audio circuits (+ and -) to the radio. The voltage amount and rate of change is dependent upon the type of signal being received. The radio then processes these signals and passes the audio to the appropriate speakers or amplifier.
The communication interface module (CIM) receives information from a specific navigation antenna located on the outside of the vehicle. The navigation antenna is connected to the CIM via a shielded coaxial cable. The antenna cable also provides a path for DC current for powering the antenna.
The communication interface module (CIM) provides the cellular microphone with a supplied voltage on the cellular microphone signal circuit. When the microphone is in use, voice data from the user is sent back to the CIM on the signal circuit. The CIM provides a ground for the microphone via the low reference circuit.
The vehicle navigation radio and OnStar® system both utilize the cellular microphone to receive voice commands. The navigation radio receives an audio voice signal from the communication interface module (CIM).
The vehicle navigation radio and OnStar® system both utilize the cellular microphone to receive voice commands. The navigation radio receives an audio voice signal from the vehicle communication interface module (VCIM).
When an OnStar® keypress is made, a serial data message is sent to the audio system to mute all radio functions and output OnStar® originated audio. After the audio system is muted, the communication interface module (CIM) transmits signals to the audio system on the audio signal and audio common circuits.
The communication interface module (CIM) has the capability of commanding the horn, initiating door lock/unlock, or operating the exterior lamps using the serial data circuits. These functions are commanded by the OnStar® Call Center per a customer request.
The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center, and OnStar® Emergency. The communication interface module (CIM) supplies the OnStar® button assembly with 10 volts via the keypad supply voltage circuit. Each of the buttons, when pressed, completes the circuit across a resistor allowing a specific voltage to be returned to the CIM over the keypad signal circuit. Depending upon the voltage range returned, the CIM is able to identify which button has been activated.
Antenna Coaxial/Connector Cable Identification Table
| SYSTEM | COAX TYPE | PURPLE | BLUE | CURRY (Mustard Yellow) | GREEN |
|---|---|---|---|---|---|
| OnStar (Cellular) | RG 58 | X | |||
| GPS | RG 174 | X | |||
| XM | RG 316 | X | |||
| XM w/High Gain Antenna Module (Cables longer than 4400 mm [14.5 Ft]) | X |
ONSTAR, GPS, XM, AM/FM-CONNECTOR IDENTIFICATION AT CIM
| CONNECTOR CONFIGURATION | OnStar (Cellular) PURPLE | GPS BLUE | XM CURRY (Mustard Yellow) | XM GREEN | AM/FM |
|---|---|---|---|---|---|
| 3 Individual Connectors | X | X | X | ||
| 2 Individual Connectors | X | X | |||
| 3 Way Connector w/3 COAX Cables | X | X | X | ||
| 3 Way Connector w/2 COAX Cables With a Separate Connector for XM | X | X | X (S) | ||
| 3 Blue 2 Way Connectors + Power Feed (Hexband) | X | X | X | ||
| 1 Connector With Splitter | X (S) | X (S) | |||
| High Gain Antenna XM 3 Individual Connectors (ver 1) | X | X | X | ||
| High Gain Antenna XM Blue 2 Way With Separate Green Connector (ver 2) | 2 way | 2 way | X |
CONNECTOR IDENTIFICATION AT ONSTAR ANTENNA BASE
AM and FM radio reception is dependent on the following components
- Radio antenna
- Coax cable between the radio antenna and the radio
- Radio
The multi-band antenna is located on the roof of the vehicle. A switched B+ output from the radio entertainment remote enable circuit is used to power the AM/FM portion of this antenna. The antenna enable circuit is also used to control the power state of the amplifier (if equipped) and the rear seat entertainment video display (if equipped).
Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier have a DC bias voltage that is one half of the battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5V DC. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound. This voltage will vary depending on what type of audio is being listened to, talk or music, and type of music, as well as the volume setting of the system. Low volume and talk settings will measure around 1V AC and less, where constant music may measure 3V AC and slightly higher. In an amplified audio system, these similar AC voltage measurements may be slightly higher on the output of the amplifier, and the typical AC voltage readings at the output of the radio are less than 1V AC.
The communication interface module (CIM) is a cellular device that allows the user to communicate data and voice signals over the national cellular network. When an OnStar keypress is made, the CIM activates and connects the system to the cellular carriers communication system by interacting with the national cellular infrastructure. The module sends and receives all cellular communications over the cellular antenna and cellular antenna coax.
The CIM is capable of interpreting voice commands received over the cellular microphone circuits. Speech recognition allows the user to speak to one computer in the vehicle, and one reached over the cellular communication network. The module attempts to understand the users command, and responds by speaking back, or by taking the appropriate action, e.g. dialing the phone.
Each item in the list below represents topics covered in detail below.
- Audio System Description
- Navigation System Components
- Navigation Radio
- Global Positioning System (GPS) Antenna
- Route Guidance
- Auxiliary RCA Video Jacks (If Equipped)
- Voice Recognition
- Points of Interest
Audio System Description
The Navigation radio operates similar to a traditional radio. For information on the audio description and operation, refer to Radio/Audio System Description and Operation .
OnStar Description and Operation
This OnStar® system consists of the following components
- Communication Interface Module (CIM)
- OnStar® button assembly
- Microphone
- Cellular antenna
- Navigation antenna
- Bluetooth ® antenna (If Equipped)
- Back Up Battery (BUB) (If Equipped)
This system also interfaces with the factory installed vehicle audio system.
Mobile Identification Number and Mobile Directory Number
The communication interface module (CIM) utilizes 2 numbers for cellular device identification, call routing and connection, a mobile identification number (MIN) and a mobile directory number (MDN). The MIN represents the number used by the cellular carrier for call routing purposes while the MDN represents the number dialed to reach the cellular device.
Operation of the OnStar® Speech Recognition Systems
OnStar® users communicate with 2 speech recognition systems. Speech recognition allows the user to speak to one computer in the vehicle, and one reached over a phone line. The computer tries to understand the users command, and responds by speaking back, or by taking the appropriate action, e.g. dialing the phone.
- Personal Calling uses a speech recognition system that resides in the vehicle. When the user presses the phone button, the system states, Ready, and listens for the user's command. The user can speak commands to control the hands-free phone.
- Virtual advisor is a remote speech recognition system that the caller can access by making a phone call. The user connects to virtual advisor by requesting it during personal calling use. The user is then transferred to the virtual advisor server and talks to it via a cellular connection.
The OnStar® speech recognition systems use speech technology that is designed to understand a wide range of American English speakers. Although there is no one right way to speak English, the system will work best when users try to modify their pronunciation should they encounter difficulty. Users who do not obtain good results are advised to try the tips and workarounds found in this section.
| Concern | Tip for Better Result |
|---|---|
| Noise | Noise may confuse the speech recognition system. You usually get better performance from the system in quieter conditions: The HVAC fan creates noise. Turn it down or OFF for better speech system performance. Driving at high speeds creates louder engine noise and wind noise. You may get better results at lower speeds. An open window or an open sunroof allows more noise to enter the vehicle. Close all windows for better results. Noisy rainstorms can also reduce performance. If passengers are talking while you use the speech system, it may be confused by their speech. You will get better results if all occupants of the vehicle are quiet while the system is listening for commands. |
| When to Speak | In Personal Calling, the system is only listening after it prompts you to speak. When the system prompts you to speak, you have about 5 seconds to respond. If the system does not hear a response, it will prompt you again, or cancel the transaction. If you begin to speak too soon, it will tell you "Slower, please." Try pausing for a half second before speaking. In the Virtual Advisor, the system is always listening for commands, even while it is speaking. |
| How to Speak | Speak forcefully, and clearly. The noisier the environment, the louder you need to speak. If you are in the driver seat, speak facing the front of the car. If you are a passenger, speak facing the rearview mirror. Speak calmly, and naturally. The system may sometimes fail your repeated attempts to give a command. If your speech is distorted by shouting or frustration, this may cause more errors. People with high-pitched voices may have better results by speaking in a deeper, lower-pitched voice. However, do not lower the volume of the voice. Avoid speaking with a rising intonation, like asking a question. Use a flat or falling intonation, like giving an answer. |
| What to Say | Personal Calling: One-word commands The Personal Calling system listens for only one word at a time. There are some exceptions, 2-word phrases that are spoken and understood as a single word, e.g. "virtual advisor", "voice feedback", and "my number". You can enter phone numbers only one digit at a time, and the system repeats each digit as it hears it. Say "Help" at the Ready prompt to hear the list of Personal Calling commands. Virtual Advisor can understand sentences with more than one word. It also expects to hear a 4-digit number all at once when it asks for your PIN. Say, "What are my choices?" to hear a list of commands that the Virtual Advisor understands. |
| Entering a phone number | If you have trouble getting numbers correctly into the system, store your frequently-called number in the directory, so the system will remember them. After you have stored a number with a nametag, then you simply say "call" and the nametag in order to call the number. If the system cannot understand your numbers, ask another person to help you enter your frequently-called numbers. This person can speak the numbers, then you can speak the nametag. |
| Storing or dialing a number | When you have finished speaking your phone number, you do not need to say "store" or "dial" to indicate that you are done. If you pause and say nothing, the system will ask you if you want to store or dial. Say "yes". |
| Creating nametags | Short nametags that are similar may be easily confused by the system. You may get better recognition of your nametags if you make them longer, for example "George Washington" without pause, instead of "George" only. If you want to use nametags while driving, it is best to store the nametag with some vehicle noise in the background. If you are in park while you are storing nametags, you can turn the fan on low or open windows in order to create some background noise. |
| Virtual Advisor 4-digit PIN | Say the 4 digits in a natural way, without pausing between digits. |
| Interrupting | When the Virtual Advisor is speaking, you can interrupt it with another command. The first word in your command helps to get its attention. If the Virtual Advisor has trouble understanding your commands when you interrupt, try speaking the first word loudly and clearly, then pause for an instant, then continue with the rest of the command. For example: "Get .. my weather" or "Lookup... a quote for General Motors". |
General Tips for Better Speech Recognition
Radio/Audio System Description and Operation
The entertainment system on this vehicle may have several different configurations available to it. To determine the specific configuration of the vehicle, please see the Service Parts ID Label, and refer to RPO Code List (Acadia) or RPO Code List (Traverse) or RPO Code List (Enclave) or RPO Code List (Outlook) .
The entertainment system on this vehicle is configured with either a base or an uplevel system. The base and uplevel systems each contain a radio, antenna, speakers, and on some systems an audio amplifier. The uplevel system differs from the base system by providing the customer with enhanced audio system features. Some of those features may include the radio data system (RDS), an audio amplifier, programmable equalizer (EQ), and digital satellite radio (U2K).
Each item in the list below represents topics covered in detail below.
- Radio Circuit Operation
- Antenna System
- AM/FM Reception
- Digital Radio Receiver
- Speaker Operation
- Audio Amplifier
- Radio Data System (RDS)
- Radio Data System (RDS) Messages
- MP3/CD Formatting Information for MP3/CD Radios (If equipped)
- Integral Multi Disc CD Changer (IMDX)
- Rear Seat Audio (RSA)
- Rear Seat Entertainment (RSE)
- Radio Error Messages
- Theft Deterrent
- OnStar ®
- Steering Wheel Controls
- Auxiliary Input Jack
- Personal Audio Link (PAL)
- Noise Compensation
- Speed Compensated Volume (SCV)
Speaker Operation
Speakers turn electrical energy into mechanical energy to move air, using a permanent magnet and an electromagnet. The electromagnet is energized when the radio or amplifier (if equipped) delivers current to the voice coil on the speaker. The voice coil will form a north and south pole that will cause the voice coil and the speaker cone to move in relation to the permanent magnet. The current delivered to the speaker is rapidly changing alternating current (A/C). This causes the speaker cone to move in two directions producing sound. When the speaker is at rest, such as when the volume at a minimum value, the voltage applied to each side of the speaker is 1/2 ignition system voltage. This way, the speaker cone can be moved in either direction.
Amplifier Operation
The purpose of the amplifier is to increase the power of a voltage or current signal. The output signal of an amplifier may consist of the same frequencies as the input signal or it may consist of only a portion of the frequencies as in the case of a subwoofer or midrange speaker. The radio creates a low level stereo audio output signal, which is sent at the user-defined volume level to the audio amplifier. The audio amplifier amplifies the signal and sends it to the appropriate speakers.
The radio provides a remote radio control signal to control overall muting of the amplifier. The amplifier receives PWM signals on the circuit at varying duty cycle percentages for controlling the muted and unmuted functions of the amplifier.
The function table below shows the possible amplifier mute functions.
| % Duty Cycle Out | Function |
|---|---|
| 0% (Vlow Vdc) | FOUR_CHANNEL_UNMUTE |
| 50% | REAR_MUTE (input must be 2-channel) |
| 100% (Vhigh Vdc) | ALL_MUTE |
Video Entertainment System Description and Operation (Non-Headrest DVD Systems)
Each item in the list below represents topics covered in detail below.
- Rear Seat Entertainment Circuit Operation
- Rear Entertainment System Components
- DVD Player
- Playing a Disc
- DVD Messages
- Parental Control
- Video Screen
- Remote Control
- Wireless Headphones
- Stereo RCA Jacks
- Rear Seat Audio (RSA)
- Audio Outputs
- Wired Headphone Jacks
Video Entertainment System Description and Operation (Dual Headrest DVD Systems)
Each item in the list below represents topics covered in detail below.
- Dual Headrest DVD Circuit Operation
- Dual Headrest DVD System Components
- Dual Headrest DVD Player
- Playing a Disc
- DVD Messages
- Parental Control
- Video Screen
- Remote Control
- Wireless Headphones
- AUX Inputs
- Audio Outputs
- Wired Headphone Jacks